Question

[！[在此处输入图片说明] [1]] [1]我需要以下查询的帮助。

select * 
from xr.ObjectPropertyvalue 
where objectid in (
    select objectid 
    from xr.objectpropertyvalue 
    where endversion in 
             (select max(endversion) 
              from xr.ObjectPropertyValue 
              group by objectid having count(endversion) > 1
   )
 )

我想要做的是在桌面上查找具有最高版本且objectid是唯一的条目。

Ex.
    Object id 1's highest version = 3
    Object id 2 highest version =4

任何帮助都将不胜感激。

Answer 1

如果我理解正确，您可以尝试此查询（未经测试，我现在没有sql-server环境）

import UIKit

class Parent {
    var child:Child?
    deinit {
        print("deinitialized")
    }
}

class Child {
    weak var parent: Parent?
    deinit {
        print("deinitialized")
    }
}
class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        let child = Child()
        let parent = Parent()

        child.parent = parent
        parent.child = child // strong reference cycle created
    }

}

SQL查询帮助（ObjectPropertyvalue）

1 个答案: